In the field of biology, a technique for efficiently separating one type or class of cell from a complex cell suspension would have wide applications. The ability to remove certain cells from a clinical blood sample that were indicative of a particular disease state could be useful as a diagnostic for that disease.
It has been shown that cells tagged with micron sized (>1 μm) magnetic or magnetized particles can be successfully removed or separated from mixtures using magnetic devices. For the removal of desired cells, i.e., cells which provide valuable information, the desired cell population is magnetized and removed from the complex liquid mixture (so-called positive selection or positive separation). In an alternative method, the undesirable cells, i.e., cells that may prevent or alter the results of particular procedure, are magnetized and subsequently removed with a magnetic device (so-called negative selection or negative separation).
U.S. Pat. No. 6,572,778 discloses a magnetic device formed with an arrangement including four polar magnets and a plurality of interpolar magnets for providing a magnetic field that may attract magnetized particles in bio-samples toward interior walls of a piping disposed between the polar magnets and interpolar magnets. However, the strength of the magnetic field provided by this magnetic device is limited by the remanent induction (Br) of the magnets materials used therein, such that the magnetic device fails to provide the magnetic field with a sufficiently powerful attraction against the magnetized particles in the bio-samples for the purpose of improving bio-separation efficiency.